Static lib is not built for multiple architectures

We are trying to build a bundled Android App (.aab) with Multi-Abi support. For a part of our project we are using a project subdir as a static lib like described here https://wiki.qt.io/How_to_create_a_library_with_Qt_and_use_it_in_an_application (Creating a static library).

For my understanding the static lib must be generated for different architectures (e.g. staticlib_armeabi-v7a.a, staticlib_arm64-v8a.a). Instead there is only one staticlib.a file in the static-lib output path. So it seems that this lib gets overwritten by each architecture build. As a result I get an "skipping incompatible" linker error when trying to link the lib to the app.

As a workaround I created different architecure-specific .pro files for our static lib and defined each ABI in the .pro files. This worked but is very cumbersome and confusing.

Are there any other solutions to this problem? As a build system we use qmake, are there some known advantages here with cmake?